| //! Code related to processing overloaded binary and unary operators. |
| |
| use super::method::MethodCallee; |
| use super::FnCtxt; |
| use crate::Expectation; |
| use rustc_ast as ast; |
| use rustc_data_structures::packed::Pu128; |
| use rustc_errors::{codes::*, struct_span_code_err, Applicability, Diag}; |
| use rustc_hir as hir; |
| use rustc_infer::infer::type_variable::TypeVariableOrigin; |
| use rustc_infer::traits::ObligationCauseCode; |
| use rustc_middle::ty::adjustment::{ |
| Adjust, Adjustment, AllowTwoPhase, AutoBorrow, AutoBorrowMutability, |
| }; |
| use rustc_middle::ty::print::with_no_trimmed_paths; |
| use rustc_middle::ty::{self, IsSuggestable, Ty, TyCtxt, TypeVisitableExt}; |
| use rustc_session::errors::ExprParenthesesNeeded; |
| use rustc_span::source_map::Spanned; |
| use rustc_span::symbol::{sym, Ident}; |
| use rustc_span::Span; |
| use rustc_trait_selection::infer::InferCtxtExt; |
| use rustc_trait_selection::traits::error_reporting::suggestions::TypeErrCtxtExt as _; |
| use rustc_trait_selection::traits::{self, FulfillmentError, ObligationCtxt}; |
| use rustc_type_ir::TyKind::*; |
| |
| impl<'a, 'tcx> FnCtxt<'a, 'tcx> { |
| /// Checks a `a <op>= b` |
| pub fn check_binop_assign( |
| &self, |
| expr: &'tcx hir::Expr<'tcx>, |
| op: hir::BinOp, |
| lhs: &'tcx hir::Expr<'tcx>, |
| rhs: &'tcx hir::Expr<'tcx>, |
| expected: Expectation<'tcx>, |
| ) -> Ty<'tcx> { |
| let (lhs_ty, rhs_ty, return_ty) = |
| self.check_overloaded_binop(expr, lhs, rhs, op, IsAssign::Yes, expected); |
| |
| let ty = |
| if !lhs_ty.is_ty_var() && !rhs_ty.is_ty_var() && is_builtin_binop(lhs_ty, rhs_ty, op) { |
| self.enforce_builtin_binop_types(lhs.span, lhs_ty, rhs.span, rhs_ty, op); |
| self.tcx.types.unit |
| } else { |
| return_ty |
| }; |
| |
| self.check_lhs_assignable(lhs, E0067, op.span, |err| { |
| if let Some(lhs_deref_ty) = self.deref_once_mutably_for_diagnostic(lhs_ty) { |
| if self |
| .lookup_op_method( |
| (lhs, lhs_deref_ty), |
| Some((rhs, rhs_ty)), |
| Op::Binary(op, IsAssign::Yes), |
| expected, |
| ) |
| .is_ok() |
| { |
| // If LHS += RHS is an error, but *LHS += RHS is successful, then we will have |
| // emitted a better suggestion during error handling in check_overloaded_binop. |
| if self |
| .lookup_op_method( |
| (lhs, lhs_ty), |
| Some((rhs, rhs_ty)), |
| Op::Binary(op, IsAssign::Yes), |
| expected, |
| ) |
| .is_err() |
| { |
| err.downgrade_to_delayed_bug(); |
| } else { |
| // Otherwise, it's valid to suggest dereferencing the LHS here. |
| err.span_suggestion_verbose( |
| lhs.span.shrink_to_lo(), |
| "consider dereferencing the left-hand side of this operation", |
| "*", |
| Applicability::MaybeIncorrect, |
| ); |
| } |
| } |
| } |
| }); |
| |
| ty |
| } |
| |
| /// Checks a potentially overloaded binary operator. |
| pub fn check_binop( |
| &self, |
| expr: &'tcx hir::Expr<'tcx>, |
| op: hir::BinOp, |
| lhs_expr: &'tcx hir::Expr<'tcx>, |
| rhs_expr: &'tcx hir::Expr<'tcx>, |
| expected: Expectation<'tcx>, |
| ) -> Ty<'tcx> { |
| let tcx = self.tcx; |
| |
| debug!( |
| "check_binop(expr.hir_id={}, expr={:?}, op={:?}, lhs_expr={:?}, rhs_expr={:?})", |
| expr.hir_id, expr, op, lhs_expr, rhs_expr |
| ); |
| |
| match BinOpCategory::from(op) { |
| BinOpCategory::Shortcircuit => { |
| // && and || are a simple case. |
| self.check_expr_coercible_to_type(lhs_expr, tcx.types.bool, None); |
| let lhs_diverges = self.diverges.get(); |
| self.check_expr_coercible_to_type(rhs_expr, tcx.types.bool, None); |
| |
| // Depending on the LHS' value, the RHS can never execute. |
| self.diverges.set(lhs_diverges); |
| |
| tcx.types.bool |
| } |
| _ => { |
| // Otherwise, we always treat operators as if they are |
| // overloaded. This is the way to be most flexible w/r/t |
| // types that get inferred. |
| let (lhs_ty, rhs_ty, return_ty) = self.check_overloaded_binop( |
| expr, |
| lhs_expr, |
| rhs_expr, |
| op, |
| IsAssign::No, |
| expected, |
| ); |
| |
| // Supply type inference hints if relevant. Probably these |
| // hints should be enforced during select as part of the |
| // `consider_unification_despite_ambiguity` routine, but this |
| // more convenient for now. |
| // |
| // The basic idea is to help type inference by taking |
| // advantage of things we know about how the impls for |
| // scalar types are arranged. This is important in a |
| // scenario like `1_u32 << 2`, because it lets us quickly |
| // deduce that the result type should be `u32`, even |
| // though we don't know yet what type 2 has and hence |
| // can't pin this down to a specific impl. |
| if !lhs_ty.is_ty_var() |
| && !rhs_ty.is_ty_var() |
| && is_builtin_binop(lhs_ty, rhs_ty, op) |
| { |
| let builtin_return_ty = self.enforce_builtin_binop_types( |
| lhs_expr.span, |
| lhs_ty, |
| rhs_expr.span, |
| rhs_ty, |
| op, |
| ); |
| self.demand_eqtype(expr.span, builtin_return_ty, return_ty); |
| builtin_return_ty |
| } else { |
| return_ty |
| } |
| } |
| } |
| } |
| |
| fn enforce_builtin_binop_types( |
| &self, |
| lhs_span: Span, |
| lhs_ty: Ty<'tcx>, |
| rhs_span: Span, |
| rhs_ty: Ty<'tcx>, |
| op: hir::BinOp, |
| ) -> Ty<'tcx> { |
| debug_assert!(is_builtin_binop(lhs_ty, rhs_ty, op)); |
| |
| // Special-case a single layer of referencing, so that things like `5.0 + &6.0f32` work. |
| // (See https://github.com/rust-lang/rust/issues/57447.) |
| let (lhs_ty, rhs_ty) = (deref_ty_if_possible(lhs_ty), deref_ty_if_possible(rhs_ty)); |
| |
| let tcx = self.tcx; |
| match BinOpCategory::from(op) { |
| BinOpCategory::Shortcircuit => { |
| self.demand_suptype(lhs_span, tcx.types.bool, lhs_ty); |
| self.demand_suptype(rhs_span, tcx.types.bool, rhs_ty); |
| tcx.types.bool |
| } |
| |
| BinOpCategory::Shift => { |
| // result type is same as LHS always |
| lhs_ty |
| } |
| |
| BinOpCategory::Math | BinOpCategory::Bitwise => { |
| // both LHS and RHS and result will have the same type |
| self.demand_suptype(rhs_span, lhs_ty, rhs_ty); |
| lhs_ty |
| } |
| |
| BinOpCategory::Comparison => { |
| // both LHS and RHS and result will have the same type |
| self.demand_suptype(rhs_span, lhs_ty, rhs_ty); |
| tcx.types.bool |
| } |
| } |
| } |
| |
| fn check_overloaded_binop( |
| &self, |
| expr: &'tcx hir::Expr<'tcx>, |
| lhs_expr: &'tcx hir::Expr<'tcx>, |
| rhs_expr: &'tcx hir::Expr<'tcx>, |
| op: hir::BinOp, |
| is_assign: IsAssign, |
| expected: Expectation<'tcx>, |
| ) -> (Ty<'tcx>, Ty<'tcx>, Ty<'tcx>) { |
| debug!( |
| "check_overloaded_binop(expr.hir_id={}, op={:?}, is_assign={:?})", |
| expr.hir_id, op, is_assign |
| ); |
| |
| let lhs_ty = match is_assign { |
| IsAssign::No => { |
| // Find a suitable supertype of the LHS expression's type, by coercing to |
| // a type variable, to pass as the `Self` to the trait, avoiding invariant |
| // trait matching creating lifetime constraints that are too strict. |
| // e.g., adding `&'a T` and `&'b T`, given `&'x T: Add<&'x T>`, will result |
| // in `&'a T <: &'x T` and `&'b T <: &'x T`, instead of `'a = 'b = 'x`. |
| let lhs_ty = self.check_expr(lhs_expr); |
| let fresh_var = self |
| .next_ty_var(TypeVariableOrigin { param_def_id: None, span: lhs_expr.span }); |
| self.demand_coerce(lhs_expr, lhs_ty, fresh_var, Some(rhs_expr), AllowTwoPhase::No) |
| } |
| IsAssign::Yes => { |
| // rust-lang/rust#52126: We have to use strict |
| // equivalence on the LHS of an assign-op like `+=`; |
| // overwritten or mutably-borrowed places cannot be |
| // coerced to a supertype. |
| self.check_expr(lhs_expr) |
| } |
| }; |
| let lhs_ty = self.resolve_vars_with_obligations(lhs_ty); |
| |
| // N.B., as we have not yet type-checked the RHS, we don't have the |
| // type at hand. Make a variable to represent it. The whole reason |
| // for this indirection is so that, below, we can check the expr |
| // using this variable as the expected type, which sometimes lets |
| // us do better coercions than we would be able to do otherwise, |
| // particularly for things like `String + &String`. |
| let rhs_ty_var = |
| self.next_ty_var(TypeVariableOrigin { param_def_id: None, span: rhs_expr.span }); |
| |
| let result = self.lookup_op_method( |
| (lhs_expr, lhs_ty), |
| Some((rhs_expr, rhs_ty_var)), |
| Op::Binary(op, is_assign), |
| expected, |
| ); |
| |
| // see `NB` above |
| let rhs_ty = self.check_expr_coercible_to_type(rhs_expr, rhs_ty_var, Some(lhs_expr)); |
| let rhs_ty = self.resolve_vars_with_obligations(rhs_ty); |
| |
| let return_ty = match result { |
| Ok(method) => { |
| let by_ref_binop = !op.node.is_by_value(); |
| if is_assign == IsAssign::Yes || by_ref_binop { |
| if let ty::Ref(region, _, mutbl) = method.sig.inputs()[0].kind() { |
| let mutbl = AutoBorrowMutability::new(*mutbl, AllowTwoPhase::Yes); |
| let autoref = Adjustment { |
| kind: Adjust::Borrow(AutoBorrow::Ref(*region, mutbl)), |
| target: method.sig.inputs()[0], |
| }; |
| self.apply_adjustments(lhs_expr, vec![autoref]); |
| } |
| } |
| if by_ref_binop { |
| if let ty::Ref(region, _, mutbl) = method.sig.inputs()[1].kind() { |
| // Allow two-phase borrows for binops in initial deployment |
| // since they desugar to methods |
| let mutbl = AutoBorrowMutability::new(*mutbl, AllowTwoPhase::Yes); |
| |
| let autoref = Adjustment { |
| kind: Adjust::Borrow(AutoBorrow::Ref(*region, mutbl)), |
| target: method.sig.inputs()[1], |
| }; |
| // HACK(eddyb) Bypass checks due to reborrows being in |
| // some cases applied on the RHS, on top of which we need |
| // to autoref, which is not allowed by apply_adjustments. |
| // self.apply_adjustments(rhs_expr, vec![autoref]); |
| self.typeck_results |
| .borrow_mut() |
| .adjustments_mut() |
| .entry(rhs_expr.hir_id) |
| .or_default() |
| .push(autoref); |
| } |
| } |
| self.write_method_call_and_enforce_effects(expr.hir_id, expr.span, method); |
| |
| method.sig.output() |
| } |
| // error types are considered "builtin" |
| Err(_) if lhs_ty.references_error() || rhs_ty.references_error() => { |
| Ty::new_misc_error(self.tcx) |
| } |
| Err(errors) => { |
| let (_, trait_def_id) = |
| lang_item_for_op(self.tcx, Op::Binary(op, is_assign), op.span); |
| let missing_trait = trait_def_id |
| .map(|def_id| with_no_trimmed_paths!(self.tcx.def_path_str(def_id))); |
| let (mut err, output_def_id) = match is_assign { |
| IsAssign::Yes => { |
| let mut err = struct_span_code_err!( |
| self.dcx(), |
| expr.span, |
| E0368, |
| "binary assignment operation `{}=` cannot be applied to type `{}`", |
| op.node.as_str(), |
| lhs_ty, |
| ); |
| err.span_label( |
| lhs_expr.span, |
| format!("cannot use `{}=` on type `{}`", op.node.as_str(), lhs_ty), |
| ); |
| self.note_unmet_impls_on_type(&mut err, errors, false); |
| (err, None) |
| } |
| IsAssign::No => { |
| let message = match op.node { |
| hir::BinOpKind::Add => { |
| format!("cannot add `{rhs_ty}` to `{lhs_ty}`") |
| } |
| hir::BinOpKind::Sub => { |
| format!("cannot subtract `{rhs_ty}` from `{lhs_ty}`") |
| } |
| hir::BinOpKind::Mul => { |
| format!("cannot multiply `{lhs_ty}` by `{rhs_ty}`") |
| } |
| hir::BinOpKind::Div => { |
| format!("cannot divide `{lhs_ty}` by `{rhs_ty}`") |
| } |
| hir::BinOpKind::Rem => { |
| format!( |
| "cannot calculate the remainder of `{lhs_ty}` divided by `{rhs_ty}`" |
| ) |
| } |
| hir::BinOpKind::BitAnd => { |
| format!("no implementation for `{lhs_ty} & {rhs_ty}`") |
| } |
| hir::BinOpKind::BitXor => { |
| format!("no implementation for `{lhs_ty} ^ {rhs_ty}`") |
| } |
| hir::BinOpKind::BitOr => { |
| format!("no implementation for `{lhs_ty} | {rhs_ty}`") |
| } |
| hir::BinOpKind::Shl => { |
| format!("no implementation for `{lhs_ty} << {rhs_ty}`") |
| } |
| hir::BinOpKind::Shr => { |
| format!("no implementation for `{lhs_ty} >> {rhs_ty}`") |
| } |
| _ => format!( |
| "binary operation `{}` cannot be applied to type `{}`", |
| op.node.as_str(), |
| lhs_ty |
| ), |
| }; |
| let output_def_id = trait_def_id.and_then(|def_id| { |
| self.tcx |
| .associated_item_def_ids(def_id) |
| .iter() |
| .find(|item_def_id| { |
| self.tcx.associated_item(*item_def_id).name == sym::Output |
| }) |
| .cloned() |
| }); |
| let mut err = |
| struct_span_code_err!(self.dcx(), op.span, E0369, "{message}"); |
| if !lhs_expr.span.eq(&rhs_expr.span) { |
| err.span_label(lhs_expr.span, lhs_ty.to_string()); |
| err.span_label(rhs_expr.span, rhs_ty.to_string()); |
| } |
| let suggest_derive = self.can_eq(self.param_env, lhs_ty, rhs_ty); |
| self.note_unmet_impls_on_type(&mut err, errors, suggest_derive); |
| (err, output_def_id) |
| } |
| }; |
| |
| // Try to suggest a semicolon if it's `A \n *B` where `B` is a place expr |
| let maybe_missing_semi = self.check_for_missing_semi(expr, &mut err); |
| |
| // We defer to the later error produced by `check_lhs_assignable`. |
| // We only downgrade this if it's the LHS, though. |
| if maybe_missing_semi |
| && let hir::Node::Expr(parent) = self.tcx.parent_hir_node(expr.hir_id) |
| && let hir::ExprKind::Assign(lhs, _, _) = parent.kind |
| && lhs.hir_id == expr.hir_id |
| { |
| err.downgrade_to_delayed_bug(); |
| } |
| |
| let suggest_deref_binop = |err: &mut Diag<'_, _>, lhs_deref_ty: Ty<'tcx>| { |
| if self |
| .lookup_op_method( |
| (lhs_expr, lhs_deref_ty), |
| Some((rhs_expr, rhs_ty)), |
| Op::Binary(op, is_assign), |
| expected, |
| ) |
| .is_ok() |
| { |
| let msg = format!( |
| "`{}{}` can be used on `{}` if you dereference the left-hand side", |
| op.node.as_str(), |
| match is_assign { |
| IsAssign::Yes => "=", |
| IsAssign::No => "", |
| }, |
| lhs_deref_ty, |
| ); |
| err.span_suggestion_verbose( |
| lhs_expr.span.shrink_to_lo(), |
| msg, |
| "*", |
| rustc_errors::Applicability::MachineApplicable, |
| ); |
| } |
| }; |
| |
| let suggest_different_borrow = |
| |err: &mut Diag<'_, _>, |
| lhs_adjusted_ty, |
| lhs_new_mutbl: Option<ast::Mutability>, |
| rhs_adjusted_ty, |
| rhs_new_mutbl: Option<ast::Mutability>| { |
| if self |
| .lookup_op_method( |
| (lhs_expr, lhs_adjusted_ty), |
| Some((rhs_expr, rhs_adjusted_ty)), |
| Op::Binary(op, is_assign), |
| expected, |
| ) |
| .is_ok() |
| { |
| let op_str = op.node.as_str(); |
| err.note(format!("an implementation for `{lhs_adjusted_ty} {op_str} {rhs_adjusted_ty}` exists")); |
| |
| if let Some(lhs_new_mutbl) = lhs_new_mutbl |
| && let Some(rhs_new_mutbl) = rhs_new_mutbl |
| && lhs_new_mutbl.is_not() |
| && rhs_new_mutbl.is_not() |
| { |
| err.multipart_suggestion_verbose( |
| "consider reborrowing both sides", |
| vec![ |
| (lhs_expr.span.shrink_to_lo(), "&*".to_string()), |
| (rhs_expr.span.shrink_to_lo(), "&*".to_string()), |
| ], |
| rustc_errors::Applicability::MachineApplicable, |
| ); |
| } else { |
| let mut suggest_new_borrow = |
| |new_mutbl: ast::Mutability, sp: Span| { |
| // Can reborrow (&mut -> &) |
| if new_mutbl.is_not() { |
| err.span_suggestion_verbose( |
| sp.shrink_to_lo(), |
| "consider reborrowing this side", |
| "&*", |
| rustc_errors::Applicability::MachineApplicable, |
| ); |
| // Works on &mut but have & |
| } else { |
| err.span_help( |
| sp, |
| "consider making this expression a mutable borrow", |
| ); |
| } |
| }; |
| |
| if let Some(lhs_new_mutbl) = lhs_new_mutbl { |
| suggest_new_borrow(lhs_new_mutbl, lhs_expr.span); |
| } |
| if let Some(rhs_new_mutbl) = rhs_new_mutbl { |
| suggest_new_borrow(rhs_new_mutbl, rhs_expr.span); |
| } |
| } |
| } |
| }; |
| |
| let is_compatible_after_call = |lhs_ty, rhs_ty| { |
| self.lookup_op_method( |
| (lhs_expr, lhs_ty), |
| Some((rhs_expr, rhs_ty)), |
| Op::Binary(op, is_assign), |
| expected, |
| ) |
| .is_ok() |
| // Suggest calling even if, after calling, the types don't |
| // implement the operator, since it'll lead to better |
| // diagnostics later. |
| || self.can_eq(self.param_env, lhs_ty, rhs_ty) |
| }; |
| |
| // We should suggest `a + b` => `*a + b` if `a` is copy, and suggest |
| // `a += b` => `*a += b` if a is a mut ref. |
| if !op.span.can_be_used_for_suggestions() { |
| // Suppress suggestions when lhs and rhs are not in the same span as the error |
| } else if is_assign == IsAssign::Yes |
| && let Some(lhs_deref_ty) = self.deref_once_mutably_for_diagnostic(lhs_ty) |
| { |
| suggest_deref_binop(&mut err, lhs_deref_ty); |
| } else if is_assign == IsAssign::No |
| && let Ref(region, lhs_deref_ty, mutbl) = lhs_ty.kind() |
| { |
| if self.type_is_copy_modulo_regions(self.param_env, *lhs_deref_ty) { |
| suggest_deref_binop(&mut err, *lhs_deref_ty); |
| } else { |
| let lhs_inv_mutbl = mutbl.invert(); |
| let lhs_inv_mutbl_ty = |
| Ty::new_ref(self.tcx, *region, *lhs_deref_ty, lhs_inv_mutbl); |
| |
| suggest_different_borrow( |
| &mut err, |
| lhs_inv_mutbl_ty, |
| Some(lhs_inv_mutbl), |
| rhs_ty, |
| None, |
| ); |
| |
| if let Ref(region, rhs_deref_ty, mutbl) = rhs_ty.kind() { |
| let rhs_inv_mutbl = mutbl.invert(); |
| let rhs_inv_mutbl_ty = |
| Ty::new_ref(self.tcx, *region, *rhs_deref_ty, rhs_inv_mutbl); |
| |
| suggest_different_borrow( |
| &mut err, |
| lhs_ty, |
| None, |
| rhs_inv_mutbl_ty, |
| Some(rhs_inv_mutbl), |
| ); |
| suggest_different_borrow( |
| &mut err, |
| lhs_inv_mutbl_ty, |
| Some(lhs_inv_mutbl), |
| rhs_inv_mutbl_ty, |
| Some(rhs_inv_mutbl), |
| ); |
| } |
| } |
| } else if self.suggest_fn_call(&mut err, lhs_expr, lhs_ty, |lhs_ty| { |
| is_compatible_after_call(lhs_ty, rhs_ty) |
| }) || self.suggest_fn_call(&mut err, rhs_expr, rhs_ty, |rhs_ty| { |
| is_compatible_after_call(lhs_ty, rhs_ty) |
| }) || self.suggest_two_fn_call( |
| &mut err, |
| rhs_expr, |
| rhs_ty, |
| lhs_expr, |
| lhs_ty, |
| |lhs_ty, rhs_ty| is_compatible_after_call(lhs_ty, rhs_ty), |
| ) { |
| // Cool |
| } |
| |
| if let Some(missing_trait) = missing_trait { |
| if op.node == hir::BinOpKind::Add |
| && self.check_str_addition( |
| lhs_expr, rhs_expr, lhs_ty, rhs_ty, &mut err, is_assign, op, |
| ) |
| { |
| // This has nothing here because it means we did string |
| // concatenation (e.g., "Hello " + "World!"). This means |
| // we don't want the note in the else clause to be emitted |
| } else if lhs_ty.has_non_region_param() { |
| // Look for a TraitPredicate in the Fulfillment errors, |
| // and use it to generate a suggestion. |
| // |
| // Note that lookup_op_method must be called again but |
| // with a specific rhs_ty instead of a placeholder so |
| // the resulting predicate generates a more specific |
| // suggestion for the user. |
| let errors = self |
| .lookup_op_method( |
| (lhs_expr, lhs_ty), |
| Some((rhs_expr, rhs_ty)), |
| Op::Binary(op, is_assign), |
| expected, |
| ) |
| .unwrap_err(); |
| if !errors.is_empty() { |
| for error in errors { |
| if let Some(trait_pred) = |
| error.obligation.predicate.to_opt_poly_trait_pred() |
| { |
| let output_associated_item = match error.obligation.cause.code() |
| { |
| ObligationCauseCode::BinOp { |
| output_ty: Some(output_ty), |
| .. |
| } => { |
| // Make sure that we're attaching `Output = ..` to the right trait predicate |
| if let Some(output_def_id) = output_def_id |
| && let Some(trait_def_id) = trait_def_id |
| && self.tcx.parent(output_def_id) == trait_def_id |
| && let Some(output_ty) = output_ty |
| .make_suggestable(self.tcx, false, None) |
| { |
| Some(("Output", output_ty)) |
| } else { |
| None |
| } |
| } |
| _ => None, |
| }; |
| |
| self.err_ctxt().suggest_restricting_param_bound( |
| &mut err, |
| trait_pred, |
| output_associated_item, |
| self.body_id, |
| ); |
| } |
| } |
| } else { |
| // When we know that a missing bound is responsible, we don't show |
| // this note as it is redundant. |
| err.note(format!( |
| "the trait `{missing_trait}` is not implemented for `{lhs_ty}`" |
| )); |
| } |
| } |
| } |
| |
| // Suggest using `add`, `offset` or `offset_from` for pointer - {integer}, |
| // pointer + {integer} or pointer - pointer. |
| if op.span.can_be_used_for_suggestions() { |
| match op.node { |
| hir::BinOpKind::Add if lhs_ty.is_unsafe_ptr() && rhs_ty.is_integral() => { |
| err.multipart_suggestion( |
| "consider using `wrapping_add` or `add` for pointer + {integer}", |
| vec![ |
| ( |
| lhs_expr.span.between(rhs_expr.span), |
| ".wrapping_add(".to_owned(), |
| ), |
| (rhs_expr.span.shrink_to_hi(), ")".to_owned()), |
| ], |
| Applicability::MaybeIncorrect, |
| ); |
| } |
| hir::BinOpKind::Sub => { |
| if lhs_ty.is_unsafe_ptr() && rhs_ty.is_integral() { |
| err.multipart_suggestion( |
| "consider using `wrapping_sub` or `sub` for pointer - {integer}", |
| vec![ |
| (lhs_expr.span.between(rhs_expr.span), ".wrapping_sub(".to_owned()), |
| (rhs_expr.span.shrink_to_hi(), ")".to_owned()), |
| ], |
| Applicability::MaybeIncorrect |
| ); |
| } |
| |
| if lhs_ty.is_unsafe_ptr() && rhs_ty.is_unsafe_ptr() { |
| err.multipart_suggestion( |
| "consider using `offset_from` for pointer - pointer if the pointers point to the same allocation", |
| vec![ |
| (lhs_expr.span.shrink_to_lo(), "unsafe { ".to_owned()), |
| (lhs_expr.span.between(rhs_expr.span), ".offset_from(".to_owned()), |
| (rhs_expr.span.shrink_to_hi(), ") }".to_owned()), |
| ], |
| Applicability::MaybeIncorrect |
| ); |
| } |
| } |
| _ => {} |
| } |
| } |
| |
| let reported = err.emit(); |
| Ty::new_error(self.tcx, reported) |
| } |
| }; |
| |
| (lhs_ty, rhs_ty, return_ty) |
| } |
| |
| /// Provide actionable suggestions when trying to add two strings with incorrect types, |
| /// like `&str + &str`, `String + String` and `&str + &String`. |
| /// |
| /// If this function returns `true` it means a note was printed, so we don't need |
| /// to print the normal "implementation of `std::ops::Add` might be missing" note |
| fn check_str_addition( |
| &self, |
| lhs_expr: &'tcx hir::Expr<'tcx>, |
| rhs_expr: &'tcx hir::Expr<'tcx>, |
| lhs_ty: Ty<'tcx>, |
| rhs_ty: Ty<'tcx>, |
| err: &mut Diag<'_>, |
| is_assign: IsAssign, |
| op: hir::BinOp, |
| ) -> bool { |
| let str_concat_note = "string concatenation requires an owned `String` on the left"; |
| let rm_borrow_msg = "remove the borrow to obtain an owned `String`"; |
| let to_owned_msg = "create an owned `String` from a string reference"; |
| |
| let string_type = self.tcx.lang_items().string(); |
| let is_std_string = |
| |ty: Ty<'tcx>| ty.ty_adt_def().is_some_and(|ty_def| Some(ty_def.did()) == string_type); |
| |
| match (lhs_ty.kind(), rhs_ty.kind()) { |
| (&Ref(_, l_ty, _), &Ref(_, r_ty, _)) // &str or &String + &str, &String or &&str |
| if (*l_ty.kind() == Str || is_std_string(l_ty)) |
| && (*r_ty.kind() == Str |
| || is_std_string(r_ty) |
| || matches!( |
| r_ty.kind(), Ref(_, inner_ty, _) if *inner_ty.kind() == Str |
| )) => |
| { |
| if let IsAssign::No = is_assign { // Do not supply this message if `&str += &str` |
| err.span_label(op.span, "`+` cannot be used to concatenate two `&str` strings"); |
| err.note(str_concat_note); |
| if let hir::ExprKind::AddrOf(_, _, lhs_inner_expr) = lhs_expr.kind { |
| err.span_suggestion_verbose( |
| lhs_expr.span.until(lhs_inner_expr.span), |
| rm_borrow_msg, |
| "", |
| Applicability::MachineApplicable |
| ); |
| } else { |
| err.span_suggestion_verbose( |
| lhs_expr.span.shrink_to_hi(), |
| to_owned_msg, |
| ".to_owned()", |
| Applicability::MachineApplicable |
| ); |
| } |
| } |
| true |
| } |
| (&Ref(_, l_ty, _), &Adt(..)) // Handle `&str` & `&String` + `String` |
| if (*l_ty.kind() == Str || is_std_string(l_ty)) && is_std_string(rhs_ty) => |
| { |
| err.span_label( |
| op.span, |
| "`+` cannot be used to concatenate a `&str` with a `String`", |
| ); |
| match is_assign { |
| IsAssign::No => { |
| let sugg_msg; |
| let lhs_sugg = if let hir::ExprKind::AddrOf(_, _, lhs_inner_expr) = lhs_expr.kind { |
| sugg_msg = "remove the borrow on the left and add one on the right"; |
| (lhs_expr.span.until(lhs_inner_expr.span), "".to_owned()) |
| } else { |
| sugg_msg = "create an owned `String` on the left and add a borrow on the right"; |
| (lhs_expr.span.shrink_to_hi(), ".to_owned()".to_owned()) |
| }; |
| let suggestions = vec![ |
| lhs_sugg, |
| (rhs_expr.span.shrink_to_lo(), "&".to_owned()), |
| ]; |
| err.multipart_suggestion_verbose( |
| sugg_msg, |
| suggestions, |
| Applicability::MachineApplicable, |
| ); |
| } |
| IsAssign::Yes => { |
| err.note(str_concat_note); |
| } |
| } |
| true |
| } |
| _ => false, |
| } |
| } |
| |
| pub fn check_user_unop( |
| &self, |
| ex: &'tcx hir::Expr<'tcx>, |
| operand_ty: Ty<'tcx>, |
| op: hir::UnOp, |
| expected: Expectation<'tcx>, |
| ) -> Ty<'tcx> { |
| assert!(op.is_by_value()); |
| match self.lookup_op_method((ex, operand_ty), None, Op::Unary(op, ex.span), expected) { |
| Ok(method) => { |
| self.write_method_call_and_enforce_effects(ex.hir_id, ex.span, method); |
| method.sig.output() |
| } |
| Err(errors) => { |
| let actual = self.resolve_vars_if_possible(operand_ty); |
| let guar = actual.error_reported().err().unwrap_or_else(|| { |
| let mut err = struct_span_code_err!( |
| self.dcx(), |
| ex.span, |
| E0600, |
| "cannot apply unary operator `{}` to type `{}`", |
| op.as_str(), |
| actual |
| ); |
| err.span_label( |
| ex.span, |
| format!("cannot apply unary operator `{}`", op.as_str()), |
| ); |
| |
| if operand_ty.has_non_region_param() { |
| let predicates = errors.iter().filter_map(|error| { |
| error.obligation.predicate.to_opt_poly_trait_pred() |
| }); |
| for pred in predicates { |
| self.err_ctxt().suggest_restricting_param_bound( |
| &mut err, |
| pred, |
| None, |
| self.body_id, |
| ); |
| } |
| } |
| |
| let sp = self.tcx.sess.source_map().start_point(ex.span).with_parent(None); |
| if let Some(sp) = |
| self.tcx.sess.psess.ambiguous_block_expr_parse.borrow().get(&sp) |
| { |
| // If the previous expression was a block expression, suggest parentheses |
| // (turning this into a binary subtraction operation instead.) |
| // for example, `{2} - 2` -> `({2}) - 2` (see src\test\ui\parser\expr-as-stmt.rs) |
| err.subdiagnostic(self.dcx(), ExprParenthesesNeeded::surrounding(*sp)); |
| } else { |
| match actual.kind() { |
| Uint(_) if op == hir::UnOp::Neg => { |
| err.note("unsigned values cannot be negated"); |
| |
| if let hir::ExprKind::Unary( |
| _, |
| hir::Expr { |
| kind: |
| hir::ExprKind::Lit(Spanned { |
| node: ast::LitKind::Int(Pu128(1), _), |
| .. |
| }), |
| .. |
| }, |
| ) = ex.kind |
| { |
| err.span_suggestion( |
| ex.span, |
| format!( |
| "you may have meant the maximum value of `{actual}`", |
| ), |
| format!("{actual}::MAX"), |
| Applicability::MaybeIncorrect, |
| ); |
| } |
| } |
| Str | Never | Char | Tuple(_) | Array(_, _) => {} |
| Ref(_, lty, _) if *lty.kind() == Str => {} |
| _ => { |
| self.note_unmet_impls_on_type(&mut err, errors, true); |
| } |
| } |
| } |
| err.emit() |
| }); |
| Ty::new_error(self.tcx, guar) |
| } |
| } |
| } |
| |
| fn lookup_op_method( |
| &self, |
| (lhs_expr, lhs_ty): (&'tcx hir::Expr<'tcx>, Ty<'tcx>), |
| opt_rhs: Option<(&'tcx hir::Expr<'tcx>, Ty<'tcx>)>, |
| op: Op, |
| expected: Expectation<'tcx>, |
| ) -> Result<MethodCallee<'tcx>, Vec<FulfillmentError<'tcx>>> { |
| let span = match op { |
| Op::Binary(op, _) => op.span, |
| Op::Unary(_, span) => span, |
| }; |
| let (opname, Some(trait_did)) = lang_item_for_op(self.tcx, op, span) else { |
| // Bail if the operator trait is not defined. |
| return Err(vec![]); |
| }; |
| |
| debug!( |
| "lookup_op_method(lhs_ty={:?}, op={:?}, opname={:?}, trait_did={:?})", |
| lhs_ty, op, opname, trait_did |
| ); |
| |
| let opname = Ident::with_dummy_span(opname); |
| let (opt_rhs_expr, opt_rhs_ty) = opt_rhs.unzip(); |
| let input_types = opt_rhs_ty.as_slice(); |
| let cause = self.cause( |
| span, |
| traits::BinOp { |
| lhs_hir_id: lhs_expr.hir_id, |
| rhs_hir_id: opt_rhs_expr.map(|expr| expr.hir_id), |
| rhs_span: opt_rhs_expr.map(|expr| expr.span), |
| rhs_is_lit: opt_rhs_expr |
| .is_some_and(|expr| matches!(expr.kind, hir::ExprKind::Lit(_))), |
| output_ty: expected.only_has_type(self), |
| }, |
| ); |
| |
| let method = self.lookup_method_in_trait( |
| cause.clone(), |
| opname, |
| trait_did, |
| lhs_ty, |
| Some(input_types), |
| ); |
| match method { |
| Some(ok) => { |
| let method = self.register_infer_ok_obligations(ok); |
| self.select_obligations_where_possible(|_| {}); |
| Ok(method) |
| } |
| None => { |
| // This path may do some inference, so make sure we've really |
| // doomed compilation so as to not accidentally stabilize new |
| // inference or something here... |
| self.dcx().span_delayed_bug(span, "this path really should be doomed..."); |
| // Guide inference for the RHS expression if it's provided -- |
| // this will allow us to better error reporting, at the expense |
| // of making some error messages a bit more specific. |
| if let Some((rhs_expr, rhs_ty)) = opt_rhs |
| && rhs_ty.is_ty_var() |
| { |
| self.check_expr_coercible_to_type(rhs_expr, rhs_ty, None); |
| } |
| |
| let (obligation, _) = |
| self.obligation_for_method(cause, trait_did, lhs_ty, Some(input_types)); |
| // FIXME: This should potentially just add the obligation to the `FnCtxt` |
| let ocx = ObligationCtxt::new(&self.infcx); |
| ocx.register_obligation(obligation); |
| Err(ocx.select_all_or_error()) |
| } |
| } |
| } |
| } |
| |
| fn lang_item_for_op( |
| tcx: TyCtxt<'_>, |
| op: Op, |
| span: Span, |
| ) -> (rustc_span::Symbol, Option<hir::def_id::DefId>) { |
| let lang = tcx.lang_items(); |
| if let Op::Binary(op, IsAssign::Yes) = op { |
| match op.node { |
| hir::BinOpKind::Add => (sym::add_assign, lang.add_assign_trait()), |
| hir::BinOpKind::Sub => (sym::sub_assign, lang.sub_assign_trait()), |
| hir::BinOpKind::Mul => (sym::mul_assign, lang.mul_assign_trait()), |
| hir::BinOpKind::Div => (sym::div_assign, lang.div_assign_trait()), |
| hir::BinOpKind::Rem => (sym::rem_assign, lang.rem_assign_trait()), |
| hir::BinOpKind::BitXor => (sym::bitxor_assign, lang.bitxor_assign_trait()), |
| hir::BinOpKind::BitAnd => (sym::bitand_assign, lang.bitand_assign_trait()), |
| hir::BinOpKind::BitOr => (sym::bitor_assign, lang.bitor_assign_trait()), |
| hir::BinOpKind::Shl => (sym::shl_assign, lang.shl_assign_trait()), |
| hir::BinOpKind::Shr => (sym::shr_assign, lang.shr_assign_trait()), |
| hir::BinOpKind::Lt |
| | hir::BinOpKind::Le |
| | hir::BinOpKind::Ge |
| | hir::BinOpKind::Gt |
| | hir::BinOpKind::Eq |
| | hir::BinOpKind::Ne |
| | hir::BinOpKind::And |
| | hir::BinOpKind::Or => { |
| span_bug!(span, "impossible assignment operation: {}=", op.node.as_str()) |
| } |
| } |
| } else if let Op::Binary(op, IsAssign::No) = op { |
| match op.node { |
| hir::BinOpKind::Add => (sym::add, lang.add_trait()), |
| hir::BinOpKind::Sub => (sym::sub, lang.sub_trait()), |
| hir::BinOpKind::Mul => (sym::mul, lang.mul_trait()), |
| hir::BinOpKind::Div => (sym::div, lang.div_trait()), |
| hir::BinOpKind::Rem => (sym::rem, lang.rem_trait()), |
| hir::BinOpKind::BitXor => (sym::bitxor, lang.bitxor_trait()), |
| hir::BinOpKind::BitAnd => (sym::bitand, lang.bitand_trait()), |
| hir::BinOpKind::BitOr => (sym::bitor, lang.bitor_trait()), |
| hir::BinOpKind::Shl => (sym::shl, lang.shl_trait()), |
| hir::BinOpKind::Shr => (sym::shr, lang.shr_trait()), |
| hir::BinOpKind::Lt => (sym::lt, lang.partial_ord_trait()), |
| hir::BinOpKind::Le => (sym::le, lang.partial_ord_trait()), |
| hir::BinOpKind::Ge => (sym::ge, lang.partial_ord_trait()), |
| hir::BinOpKind::Gt => (sym::gt, lang.partial_ord_trait()), |
| hir::BinOpKind::Eq => (sym::eq, lang.eq_trait()), |
| hir::BinOpKind::Ne => (sym::ne, lang.eq_trait()), |
| hir::BinOpKind::And | hir::BinOpKind::Or => { |
| span_bug!(span, "&& and || are not overloadable") |
| } |
| } |
| } else if let Op::Unary(hir::UnOp::Not, _) = op { |
| (sym::not, lang.not_trait()) |
| } else if let Op::Unary(hir::UnOp::Neg, _) = op { |
| (sym::neg, lang.neg_trait()) |
| } else { |
| bug!("lookup_op_method: op not supported: {:?}", op) |
| } |
| } |
| |
| // Binary operator categories. These categories summarize the behavior |
| // with respect to the builtin operations supported. |
| enum BinOpCategory { |
| /// &&, || -- cannot be overridden |
| Shortcircuit, |
| |
| /// <<, >> -- when shifting a single integer, rhs can be any |
| /// integer type. For simd, types must match. |
| Shift, |
| |
| /// +, -, etc -- takes equal types, produces same type as input, |
| /// applicable to ints/floats/simd |
| Math, |
| |
| /// &, |, ^ -- takes equal types, produces same type as input, |
| /// applicable to ints/floats/simd/bool |
| Bitwise, |
| |
| /// ==, !=, etc -- takes equal types, produces bools, except for simd, |
| /// which produce the input type |
| Comparison, |
| } |
| |
| impl BinOpCategory { |
| fn from(op: hir::BinOp) -> BinOpCategory { |
| match op.node { |
| hir::BinOpKind::Shl | hir::BinOpKind::Shr => BinOpCategory::Shift, |
| |
| hir::BinOpKind::Add |
| | hir::BinOpKind::Sub |
| | hir::BinOpKind::Mul |
| | hir::BinOpKind::Div |
| | hir::BinOpKind::Rem => BinOpCategory::Math, |
| |
| hir::BinOpKind::BitXor | hir::BinOpKind::BitAnd | hir::BinOpKind::BitOr => { |
| BinOpCategory::Bitwise |
| } |
| |
| hir::BinOpKind::Eq |
| | hir::BinOpKind::Ne |
| | hir::BinOpKind::Lt |
| | hir::BinOpKind::Le |
| | hir::BinOpKind::Ge |
| | hir::BinOpKind::Gt => BinOpCategory::Comparison, |
| |
| hir::BinOpKind::And | hir::BinOpKind::Or => BinOpCategory::Shortcircuit, |
| } |
| } |
| } |
| |
| /// Whether the binary operation is an assignment (`a += b`), or not (`a + b`) |
| #[derive(Clone, Copy, Debug, PartialEq)] |
| enum IsAssign { |
| No, |
| Yes, |
| } |
| |
| #[derive(Clone, Copy, Debug)] |
| enum Op { |
| Binary(hir::BinOp, IsAssign), |
| Unary(hir::UnOp, Span), |
| } |
| |
| /// Dereferences a single level of immutable referencing. |
| fn deref_ty_if_possible(ty: Ty<'_>) -> Ty<'_> { |
| match ty.kind() { |
| ty::Ref(_, ty, hir::Mutability::Not) => *ty, |
| _ => ty, |
| } |
| } |
| |
| /// Returns `true` if this is a built-in arithmetic operation (e.g., u32 |
| /// + u32, i16x4 == i16x4) and false if these types would have to be |
| /// overloaded to be legal. There are two reasons that we distinguish |
| /// builtin operations from overloaded ones (vs trying to drive |
| /// everything uniformly through the trait system and intrinsics or |
| /// something like that): |
| /// |
| /// 1. Builtin operations can trivially be evaluated in constants. |
| /// 2. For comparison operators applied to SIMD types the result is |
| /// not of type `bool`. For example, `i16x4 == i16x4` yields a |
| /// type like `i16x4`. This means that the overloaded trait |
| /// `PartialEq` is not applicable. |
| /// |
| /// Reason #2 is the killer. I tried for a while to always use |
| /// overloaded logic and just check the types in constants/codegen after |
| /// the fact, and it worked fine, except for SIMD types. -nmatsakis |
| fn is_builtin_binop<'tcx>(lhs: Ty<'tcx>, rhs: Ty<'tcx>, op: hir::BinOp) -> bool { |
| // Special-case a single layer of referencing, so that things like `5.0 + &6.0f32` work. |
| // (See https://github.com/rust-lang/rust/issues/57447.) |
| let (lhs, rhs) = (deref_ty_if_possible(lhs), deref_ty_if_possible(rhs)); |
| |
| match BinOpCategory::from(op) { |
| BinOpCategory::Shortcircuit => true, |
| |
| BinOpCategory::Shift => { |
| lhs.references_error() |
| || rhs.references_error() |
| || lhs.is_integral() && rhs.is_integral() |
| } |
| |
| BinOpCategory::Math => { |
| lhs.references_error() |
| || rhs.references_error() |
| || lhs.is_integral() && rhs.is_integral() |
| || lhs.is_floating_point() && rhs.is_floating_point() |
| } |
| |
| BinOpCategory::Bitwise => { |
| lhs.references_error() |
| || rhs.references_error() |
| || lhs.is_integral() && rhs.is_integral() |
| || lhs.is_floating_point() && rhs.is_floating_point() |
| || lhs.is_bool() && rhs.is_bool() |
| } |
| |
| BinOpCategory::Comparison => { |
| lhs.references_error() || rhs.references_error() || lhs.is_scalar() && rhs.is_scalar() |
| } |
| } |
| } |
